Process for the preparation of color-photographic sensitive materials using nonionic and anionic surface active agents

ABSTRACT

A PROCESS FOR PRODUCING COLOR-PHOTOGRAPHIC SENSITIVE MATERIAL COMPRISING A SUPPORT AND A SILVER HALIDE EMULSION CARRIED THEREON. THE EMULSION CONTAINS A FINELY DISPERSED COLOR-FORMING COUPLER WHICH HAS A HYDROPHOBIC RADICAL CONTAINING 9-28 CARBON ATOMS. THE COLOR-PHOTOGRAPHIC MATERIL IS FORMED BY DISPERSING THE ABOVE COUPLER IN AN AQUEOUS GELATIN SOLUTION IN THE PRESENCE OF A NONIONIC SURFACE ACTIVE AGENT OBTAINED BY THE ESTERIFICATION OF ONE TO TWO HYDROXYL GROUPS IN AN ANHYDROHEXITOL MOLECULE WITH A FATTY ACID CONTAINING 10 TO 20 CARBON ATOMS AND AN ANIONIC SURFACE ACTIVE AGENT CONTAINING BOTH A HYDROPHOBIC RADICAL CONTAINING 8 TO 30 CARBON ATOMS AND A WATER-SOLUBILIZING MO3S-OR MO3SO-GROUP WHEREIN M REPRESENTS A HYDROGEN ATOM, OR AN ALKALI METAL ATOM OR AN AMMONIUM GROUP.

United States Patent Office 3,676,141 Patented July 11, 1972 rm. Cl. arise 1/40 U.S. Cl. 96-100 25 Claims ABSTRACT OF THE DISCLOSURE A process for producing color-photographic sensitive material comprising a support and a silver halide emulsion carried thereon. The emulsion contains a finely dispersed color-forming coupler which has a hydrophobic radical containing 9-28 carbon atoms. The color-photographic material is formed by dispersing the above coupler in an aqueous gelatin solution in the presence of a nonionic surface active agent obtained by the esterification of one to two hydroxyl groups in an anhydrohexitol molecule with a fatty acid containing 10 to 20 carbon atoms and an anionic surface active agent containing both a hydrophobic radical containing 8 to 30 carbon atoms and a water-solubilizing MO S- or MO SO-group wherein M represents a hydrogen atom, or an alkali metal atom or an ammonium group.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a process for the preparation of color-photographic sensitive materials, more particularly, to a novel process for incorporating a lipophilic color coupler into a photographic emulsion.

Description of the prior art For the formation of colored photographic images in substractive color reproduction, a process is commonly employed in which the exposed silver halide grains are reduced by a developing agent of the N,N-disubstituted p-phenylenediamine type, and the oxidation product of the developing agent couples with a color-forming coupler to produce a cyan, magenta or yellow dye.

In a multilayered photographic sensitive material in which the couplers are incorporated in the silver-halide emulsion layers of corresponding spectral sensitivity, it is necessary to render the couplers non-difiusible to prevent degradation of color reproduction caused by migra tion of the couplers from one emulsion layer to another. To attain this object, it is necessary to introduce into a coupler molecule a ballast group containing at least 8 carbon atoms which remarkably reduces the diifusibility of the coupler. There have hitherto been known several means for incorporating a non-diffusible coupler in a photographic emulsion layer. Among these means, the so-called oil-protected process has been excellent because of the advantages. A color image therefrom has excellent spectral absorption properties and a high fastness to moisture and the addition of coupler in the process has very little adverse effect on the mechanical properties of gelatin in the emulsion layer.

In the oil protected process a solution obtained by dissolving a lipophilic coupler in an organic solvent is directly dispersed as fine colloidal particles into a phois dispersed into an aqueous medium to form a coupler dispersion which is then added to a photographic emulsion. The coupler used in the oil-protected process must be easily soluble in the organic solvent and for this reason it has a structure wherein a libophilic group containing at least 8 carbon atoms is combined with a coupling radical. These couplers have no water-solubilizing group such as sulfonate or sulfate group.

In the oil-protected process the coupler and the organic solvent are dispersed as very fine liquid particles. It is necessary to make the size of these particles as small as possible and the surface area of each particle as large as possible. First, since many processes included in the color formation, e.g. dissociation of the coupler, penetration of the oxidation product of the developing agent, the coupling reaction and removal of isolated products, proceed through the interfaces between the coupler particles and the aqueous medium, it is important to make the area of the interfaces large to give a high coupling reactivity to the coupler. Next, in the dry gelatin as well as in gelatin swollen by a processing liquid, the refractive index of a coupler particle is usually not completely equal to that of gelatin, so that the particles cause scattering of light and render the emulsion layer somewhat turbid. Accordingly, for high clarity of an emulsion layer having a developed color image, it is necessary to make the size of the particles as small as possible.

Fine dispersion of a lipophilic coupler in an aqueous medium has hitherto been attained by using an aqueous solution of gelatin as the dispersion medium and an anionic surface active agent as an emulsifier. For example, in U.S. Pat. 2,332,027 there are disclosed Gurdinol W (Du Pont Co., a sulfated coconut fatty alcohol) and triisopropyl-naphthalene sulfate; in U.S. Pat. 2,801,170 there is disclosed Alkanol B (sodium triisopropylnaphthalenesulfonate); and in Japanese Pat. 428,191 there is disclosed a process in which a water-soluble coupler having a sulfonate or carboxyl group and a long chain aliphatic group is used as an emulsifier.

It is well known that a variety of surface active agents are effectively used for emulsifying and dispersing oily materials in water. In these systems, the size of the resulting dispersed particles is usually 2 microns or larger. However, in the case of photographic emulsions, the particle size must be 0.5 micron or less for the reasons mentioned above. Although it was possible to disperse a lipophilic coupler into particles of 0.5 micron or less by the combination of gelatin and an anionic surface active agent mentioned above, the emulsifying process using this combination has been accompanied by troubles.

The troubles encountered by the use of a combination of gelatin and an anionic surface active agent are (especially) the tendency of the emulsion for foaming, a decrease in the emulsifying effect accompanied by foaming, and the necessity for use of a large quantity of an anionic surface active agent which makes the uniform application ofa photographic emulsion on a support difiicult.

An aqueous solution of gelatin containing an anionic surface active agent is so apt to foam that the whole solution can be made into a foam by vigorous stirring. When such a foamable liquid is stirred for emulsification, air bubbles are introduced into the liquid, the shearing force given by the emulsifying means is consumed by deformation of the air bubbles and is not effectively transmitted to the oil particles containing a coupler and, consequently, the efliciency of emulsification is extremely lowered. Some of the fine bubbles remain entrapped in the emulsion and result in pinholes in the emulsion layer formed from the emulsion. In addition, to finely emulsify a coupler to a satisfactory degree, it is necessary to use a large quantity of an anionic surface active agent. A photographic emulsion containing a large quantity of an anionic surface active agent used as an emulsifier tends to have unevenness in the thickness of the emulsion layers and the juxtaposed subsidiary gelatin layers when applied as a component layer of a color-photographic light-sensitive material, so that it is difiicult to manufacture light-sensitive materials of a uniform quality from such emulsions.

On the other hand, water-soluble nonionic surface active agents containing a poly(oxyethylene) group in the molecule, and amphotoric surface active agents which have been known to be useful the emulsification of oily materials in water, are incapable of so finely emulsifying a coupler as to be satisfactory, even if used in combination with gelatin. While cationic surface active agents exhibit a fairly satisfactory emulsifying power when used in combination with gelatin, they have adverse effects on photographic properties when added to a photographic emulsion and deteriorate the mechanical strength of a multi-layered emulsion layer.

As mentioned above, the art of sufiiciently finely dispersing a libophilic coupler for the manufacture of colorphotographic sensitive materials, allowing the coupler to coexist stably with a photographic emulsion, and affording a high reactivity to the coupler, pertains to a peculiar technical field, and most conventional emulsification techniques in the generic field are not applicable to this art.

SUMMARY OF THE INVENTION The present invention provides an improved process for producing a color-photographic sensitive material which comprises a support and a silver halide emulsion containing a finely dispersed color-forming coupler.

The process comprises dispersing said coupler, which must have a hydrophobic radical containing 9 to 28 carbon atoms, in an aqueous gelatin solution in the presence of a nonionic surface active agent obtained by the esterification of one to two hydroxyl groups in an anhydrohexitol molecule with a fatty acid containing to 20 carbon atoms and an anionic surface active agent having both a hydrophobic radical containing 8 to 30 carbon atoms and a water-solubilizing MO S- or MO SO- group wherein M repre sents a hydrogen atom, an alkali metal atom or an ammonium group.

It is an object of the present invention to provide a process for finely dispersing a libophilic coupler for color photography in an aqueous medium.

Another object of the invention is to facilitate the manufacture of color-photographic emulsions.

Still another object of the invention is to provide colorphotographic sensitive materials which can be stored stably for a long period of time and exhibit a high color-developing ability.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The process of the present invention comprises the step of dispersing a liquid, obtained by melting or dissolving in an organic solvent a libophilic coupler for color photography, into an aqueous gelatin solution in the presence of at least one anionic surface active agent and at least one nonionic surface active agent.

The anionic surface active agent used herein is a compound as contains in a molecule both a hydrophobic radical having 8 to 30 carbon atoms and a MO S- or MO 80- group wherein M represents a hydrogen atom, alkali metal atom or ammonium group.

The nonionic surface active agent used herein is selected from anhydrohexitol esters obtained by the esterification of 1 to 2 hydroxyl groups in anhydrohexitol with a fatty acid containing 10 to 20 carbon atoms, said anhydrohexitol being prepared by removing l to 2 moles of water from 1 mole of hexitol by dehydration.

The anionic and nonionic surface active agents may be added (either one of them or both of them) to the coupler liquid and the aqueous medium in any amount within their solubility range.

The libophilic coupler used here is a colorless or colored compound having a hydrophobic radical containing 9 to 28 carbon atoms as the oil-solubilizing group as well as a coupling radical which is able to couple with the oxidation product of a di-N,N-disubstituted p-phenylenediamine compound to give a dye having an absorption in the visible range. This coupler has not an extremely hydrophilic radical as the sulfonate or sulfate ester group. The coupling radical may be selected from phenolic, aromatic amino, pyrole radicals and a radical having active methylene group. Especially useful are a phenolicand naphtholic radical, an acylacetoanilide radical and a S-pyrazolone radical.

These components needed for the performance of the present invention will now be illustrated in more detail.

The anionic surface active agent suitable for use in the practice of the present invention may be selected from a wide variety of compound having both a M0 8 or MO sO-group and a hydrophobic radicalvcontaining 8 to 30 carbon atoms. Of the compounds of this type there are the detailed descriptions in, for instance, Synthesis And Applications of Surface Active Agents by R. Oda and K. Teramura (Maki Shoten Co.) and Surface Active Agents by J. W. Perry (Interscience Publication, Inc., New York).

Besides these conventional compounds, water-soluble couplers of the type having both a hydrophobic radical containing at least 9 carbon atoms and a MO' S-radical may also be suitably used as an anionic surface active agent as a dispersing agent in the practice of the present invention.

The anionic surface active agent suitably used in the practice of the present invention will be exemplified by the following compounds. I

( 0 3E 0 S OgNa.

( CnHzoO S OaNa (A3) Turkey red 011 -4) CrzHnCONHCHzCHzO S O Na CnHgs S O Na CiiHrn S OsNa (A-7) C O OH Haa m H (A-lO) CsHn- -OCH:CH2O CHzCHz-SOgNfi (A-ll) NaO S-CH-C OOCsHn C 2-CO O C sHi'i CmHw S OgN'.)

013K216 ONE SO3ND.

(Arl) N Na 0 s fl as N 4 II (it-15) S 0 K 0 NH 00-0 0 c H2O0NH l O C H3 (A-16) C15H31C-CH (11-17 cmrmoonn-o-crn SOQLI (A-ls) OH @341 ONHCiaH oaNa (A-19) on C ONHCHzCHgNHC O O H--C "H3 CHa0- cocmo ONHG The nonionic surface active agent suitable for use in the practice of the present invention is an oil-soluble material obtained by the esterification of 1 to 2 hydroxyl groups in an anhydrohexitol with a fatty acid containing 10 to 20 carbon atoms. The compounds of this type are synthesized (as disclosed in US. Pat. 2,147,241), by the reaction between an anhydrohexitol and an equimolar quantity of a higher fatty acid chloride. Examples of the anhydrohexitols are sorbitane, isosorbitol, mannitane and isomannitol, and examples of the higher fatty acids are capric acid, lauric acid, myristic acid, palmitic acid and behenic acid. The nonionic surface active agent especially useful in the practice of the present invention is exemplified by the following compounds which have HLB values in the range of from 3.5 to 9.5.

(N-l) Sorbitane sesquioleate (N-2) Sorbitane monoleate (N-3) Sorbitane monostearate (N-4) Sorbitane monopalmitate (N-5) Sorbitane monolaurate (N-6) Mannitol monooleate (N-7) Mannitane monooleate Examples of the oil-soluble couplers suitable for the practice of the present invention are disclosed, together with processes for the synthesis thereof, in US. Pat. 2,801,170, Japanese patent publication for public inspection 2,837/1964, 23,902/ 1967 and Belgian Pat. 688,083; yellow-forming couplers in Japanese patent publication for public inspection, 5,582/1967, British Pat. 1,113,038 and Belgian Pat. 692,947; magenta-forming couplers in Belgian Pats. 697,112 and 701,268; cyan-forming couplers in Japanese patent publication for public inspection 27,563/ 1964 and 11,303/19'6-7; and colored couplers in Japanese patent publication for public inspection 11,304/1967, British Pat. 1,111,342 and Belgian Pat. 701,808. These are exemplified by the following compounds:

-COCH2O ONH- (Y-3) C O O 0 H25 (n) OH: COCH2C ONH- C O O C 1211:2501) C OCHzC ONH- NHC OCHZCHQN (H; All

| C a u (L-4) on c o 0 012112501) In the practice of the present invention, it is necessary to liquefy the oil-soluble coupler by melting or dissolv ng it in an organic solvent prior to emulsification. Melting the couplers is restricted to the compounds having a melting point below about 90 C.

As the coupler solvent suitably used for finely dispersing a libophilic coupler in an aqueous medium are organic solvents which are substantially insoluble in water and have a boiling point at normal pressure above 190 C. The organic solvent may be selected from esters of carboxylic acids, phosphate esters, carboxyl amides, ethers and substituted hydrocarbons. Examples are di-n-butyl phthalate, diisooctyl phthalate, di-methoxyethyl phthalate, di-n-butyl adiphate, diisooctyl azerate, tri-n-butyl citrate, butyl laurate, di-n-butyl sebacate, tricresyl phosphate, trin butyl phosphate, tri-isooctyl phosphate, N,N-diethylcaprilamide, N,N-dimethylpalmitamide, n-butyl-m-pentadecylphenyl ether, ethyl 2,4-tert.butylphenyl ether and chlorinated paraffin.

In the practice of the present invention, a low boiling solvent or water solublehigh-boiling solvent sometimes is advantageously used for the solution of coupler along with the water-insoluble high-boiling solvent as mentioned above, e.g., propylene carbonate, ethyl acetate, butyl acetate, ethyl propionate, sec. butyl alcohol, tetrahydrofuran, cyclohexanone, dimethylformamide, diethylsulfoxide and methyl Cellosolve.

The gelatin used in the present invention may be selected from a variety of gelatins such as acid-treated gelatin, limed gelatin and enzyme-treated gelatin. The gelatins of an average molecular weight of above 30,000

are especially suitable. The gelatin may be such that have been modified by an agent such as an acylating agent.

The emulsifying apparatus suitably used in the practice of the present invention are those of the type giving a strong shearing force or an intense ultrasonic energy to the liquid being dispersed. Good results are obtainable especially by means of colloid mill, homogenizer, capillary-type emulsifying machine, liquid siren, electromagnetic ultrasonic-wave generator and emulsifying machines provided with a Pohlmar whistle.

The anhydrohexitol ester-type nonionic surface active agent used in the present invention surpresses to a great extent generation of foams and bubbles in a dispersion containing a gelatin and an anionic surface active agent and facilitates emulsification. This is evident from the results of Example 1 disclosed hereinafter.

Addition of this type of a nonionic surface active agent makes it possible to disperse a coupler into finer particles. It seems that this is attributable to the decrease of surface tension between the oily phase and the aqueous phase to a very low level by a cooperative action between the gelatin, the anonic surface active agent and the nonionic surface active agent, as well as to the increase of the emulsifying efliciency owing to the decrease of foam and bubbles as mentioned above. The comminution of the dispersed particles attained by the use of this type of a nonionic surface active agent is also evident from the results of Example 1 (set forth hereinafter).

As a result of the facilitation of the emulsification of coupler by the process of the present invention, the amount of anionic surface active agent can be reduced. The presence of an excessive amount of anionic surface active agent in a photographic emulsion causes an extreme lowering of its surface tension and, consequently, results in unevenness in the thickness of coated layers when two or more emulsions are applied simultaneously to a base. In the present invention, as a result of the reduced amount of anionic surface active agent, the uniform multi-layer application of photographic emulsions is attainable with ease. Since the anhydrohexitol esters by themselves are hardly soluble in water and have low HLB values, photo graphic emulsions containing them have a tendency to be repelled, not to be spread on a surface, and make spotted coatings when applied onto a support. The anionic surfaceactive agents defined above are now found to neutralize this repelling effect of the nonionic surface-active agents. The combination of the anionic surface-active agents, the nonionic surface-active agents and gelatin, therefore, constitutes a uniquely useful condition for the simultaneous fulfillment of good emulsification and uniform coating.

Although the amounts of the anionic surface-active agent and nonionic surface active agent used in the practice of the present invention depend on the couplers used, on the dispersing solvent and its amount, and on the type of color-photographic sensitive material, they are advantageously used in the amount of 0.5 to 50% by weight of the coupler, respectively.

The present invention will now be illustrated in detail by the following several examples.

1 1 EXAMPLE 1 A solution obtained by heating to 60 C. a mixture of 20 g. of a cyan-forming coupler of the above structural formula (C-2), 40 ml. of di-n-butyl phthalate and a varying amount of sorbitane monolaurate (N-5 was added to 200 m l. of an aqueous solution kept at 60 C. containing 15 g. of gelatin and 2.0 of sodium dodecylbenzenesulfonate (A-lZ). The resulting mixture was stirred for 25 minutes in a high speed agitator to effect emulsification. The whole emulsion thus formed was poured into a measuring cylinder and, after 10 minutes, the apparent volume (containing bubbles) of the dispersion was read to obtain the results listed in the following table.

TABLE 1 Amounts added of nonionic surface-active agent (g.)

Volume of dispersion (ml.)

In the case where no sorbitan monolaurate was added, a clear distinction could not be made between the foam and the bulk portion because of excessive foaming. Since the total liquid was full of small bubbles, a de-foaming process was indispensable prior to application of the resulting emulsion added to the coupler dispersion thus obtained. On the other hand, in the case of the dispersion containing at least 0.8 g. of the nonionic surface-active agent, only a little foaming was observed, and an emulsion layer free from pinholes was obtained even when the dispersion was added immediately after emulsification to a photographic emulsion and applied to a base.

The above experiment was repeated with varied amounts of the anionic surface active agent (A-12). The dispersions were diluted with water and subjected to determination of turbidity, and the average sizes of the coupler particles were calculated from the dependency of turbidity on wavelength. The results were as indicated in the following table.

TABLE 2.SIZES OF COUPLER PARTICLES (MICRONS) Amounts of Amounts of nonionic surface active agent (g) anionic surface active agent (g.) 0 0.4 0.8 1.6

0 0.65 (i) 0.45 (ii) 0.40 (iii) 0 35 (iv) 1 0 0.42 (v) 0.32 (vi) 0.31 (vii) 0 26 (viii) 1 5 0.35 (ix) 0.25 (x) 0.21 (xi) 0.18 (xii) 2 0 0. 29 (xiii) 0.21 (xiv) 0.18 (xv) 0.18 (xvi) Red-sensitive emulsion (containing 0.18 mole of silver chloride and 35 g. of gelatin) g 500 Coupler dispersion ml 175 Water ml 150 The surface tension of the photographic emulsion having added coupler dispersion (xiii) was as low as 33 dynes/cm., while that of the photographic emulsion added with coupler dispersion (vii) was 40 dynes/cm. The two photographic emulsions were separately applied as a first layer to a cellulose-tria'cetate film base and set by cooling. Thereover, at a rate of m./min., was applied an aqueous solution kept at 30C. and containing 0.25 g. of saponin and 2.0 g. of gelatin per 100 cc. Over the emulsion layer containing coupler dispersion (vii) it was possible to uniformly apply the second gelatin solution, while over the emulsion layer containing coupler dispersion (xiii) the second solution was expelled, and could be applied only in spots. g V g Thus, by use of the nonionic surface active agent not only was the coupler more finely dispersed, but also the emulsification of coupler and subsequent coating of emulsions were facilitated.

EXAMPLE 2 The following three dispersions of coupler were prepared.

Dispersion A A coupler solution obtained by heating a mixture of 10 g. of a cyan-forming coupler of structural formula (C-3), 0.5 g. of mannitol monooleate (N-6), 20 ml. of tri-ocresyl phosphate and 14 ml. of ethyl acetate was stirred into ml. of a 10% aqueous solution of gelatin containing 0.4 g. of sodium dodecylbenzenesulfonate (A-l2), and the resulting mixture was stirred for 5 minutes in a high-speed rotary mixer to effect emulsification.

Dispersion B A solution obtained by heating a mixture of 10 g. of a magenta-forming coupler (M-5), 0.5 g. of mannitol monooleate (N-6), 30 ml. of tri-o-cresyl phosphate and 10 ml. of ethyl acetate was added to 100 ml. of an aqueous solution kept at 60 C. and containing 0.7 g. of an anionic surface active agent (A-9) and 7 g. of gelatin, and stirred for 10 minutes in a high-speed rotary mixer to elfect emulsification.

Dispersion C A solution obtained by heating at 65 C. a mixture of 15 g. of a yellow-forming coupler (Y-S), 0.5 g. of sorbitane monooleate (N-2), 20 ml. of di-n-butyl phthalate and 30 ml. of ethyl acetate was added to 300 ml. of an aqueous solution kept at 60 C. and containing 25 g. of gelatin and 0.5 g. of a yellow-forming coupler having a sulfonate group (A-15) and subjected for 30 minutes to a vibrous agitation by means of a homogenizer.

It was observed by means of an electron microscope that in these 3 coupler dispersions the couplers had been dispersed, together with solvent, into fine oil particles of particle sizes of 0.1 to 0.4 micron. The emulsions were stable, and there was observed no agglomeration of colloidal particles, growth of the particles or crystallization of the couplers.

The total of dispersion A thus prepared was added to 360 g. of a red-sensitive photographic emulsion containing 0.11 mole of silver iodobromide and 18 g. of gelatin; the total of dispersion B was added to 540 g. of a greensensitive photographic emulsion containing 0.22 mole of silver iodobromide and 45 g. of gelatin; and the total of dispersion C was added to 500 g. of a blue-sensitive photographic emulsion containing 0.18 mole of silver iodobromide and 50 g. of elatin.

A color negative film was prepared by applying in turn, to a cellulose triacetate film base, a gelatin solution containing black colloidal silver at a dry thickness of 3 microns, applying thereover the above red-sensitive emulsion at a dry thickness of 4 microns; thereover a gelatin solution containing silver chlorobromide particles of a low light sensitivity at a dry thickness of 1.5 microns as an intermediate layer; thereover the above green-sensitive emulsion at a dry thickness of 4 microns; thereover a gelatin solution containing yellow colloidal silver at a thick ness of 2 microns as a yellow filter; thereover the above blue-sensitive emulsion at a thickness of 6 microns; and thereover a gelatin solution at a thickness of 1 micron as a protective layer. Triethylene phosphoramide was used as a hardener for the gelatin.

The film thus obtained was exposed and processed under the following conditions to give a color negative having good colorrendition-and high lucidity.

As a fixing solution there was used an acidic aqueous solution containing sodium thiosulfate and sodium sulfite, and as a bleaching solution was used a neutral aqueous solution containing potassium ferricyanide.

EXAMPLE 3 The following 3 coupler dispersions were prepared.

Dispersion D 15 g. of yellow-forming coupler of the structural formula (Y-4) was melted in boiling water. To an aqueous solution kept at 75 C. and containing 0.6 g. of an aniomcsurface active agent (A-9) and 30 g. of gelatin were added 0.8 ml. of a 30% ethyl alcohol solution of sorbitane monolaurate (N-S), and then the above coupler melt. The resulting mixture was treated 6 times repeatedly by a small colloid mill which had been heated to a temperature above 80 C. by passing therethrough hot water.

Dispersion E A solution obtained by heating a mixture of 15 g. of a magneta-forming coupler (M-l), 1.0 .g. of sorbitane monopalmitate, 1.2 g. of an anionic surface-active agent (A-l3), 10 ml. of tri-o-cresyl phosphate and 50 ml. of butyl acetate was added to 200 ml. of a 10% aqueous gelatin solution,'and the resulting mixture was treated for 20 minutes by means of a 20 kHz. electromagnetic ultrasonic generator (Sonifier, Branson Co.).

Dispersion F A solution obtained by heating a mixture of 100 g. of a cyan-forming coupler (C-6), g. of sorbitane monopalmitate, 150 ml. of di-n-butyl adipate and 250 ml. of butyl acetate was stirred into 1.5 liters of an aqueous solution containing 7 g. of a cyan-forming coupler of the above structural formula (A-18) and 100 g. of gelatin, and the resulting mixture was treated 20 times by means of an emulsifying apparatus having a Pohlman whistle.

It was observed by means of an electron microscope that in the thre coupler dispersions the coupler was dispersed into fine oil particles having particle sizes smaller than 0.4 micron. 1

All of dispersion D thus obtained was added to 1 kg. of a blue-sensitive emulsion containing 50 g. of gelatin and 0.25 mole of silver chlorobromide; all of dispersion E was added to 800 g. of a green-sensitive emulsion containing 60 g. of gelatin and 0.22 mole of silver chlorobromide; and 500 g. of dispersion F was added to 1 kg. of a redsensitive emulsion containing 70' g. of gelatin and 0.27 mole of silver chlorobromide.

To a photographic baryta paper there was applied the above blue-sensitive emulsion at a dry thickness of 5 microns; thereover a gelatin solution at a thickness of 1 micron as a first intermediate layer; thereover the greensensitive emulsion at a thickness of 4 microns; thereover a 14 gelatin solution at a thickness of 1 micron as a second intermediate layer; thereover the above red-sensitive emulsion at the thickness of 4 microns; and thereover a gelatin solution at a thickness of 1 micron as a protective layer to form a color-printing paper. Triethylenephosphoramide was used as a hardener.

Throughout all the processing there was observed no remarkable foaming and no unevenness of coating. A light-sensitive material of uniform quality was obtained.

The paper was exposed through a color negative and processed in the same manner as in Example 2 to obtain a color print having brilliant colors.

EXAMPLE 4 A solution obtained by heating a mixture of 0.5 g. of a color coupler of structural formula (L-l), 1.0 g. of a cyan-forming coupler ((E-2), 0.03 g. of sorbitane monooleate, 3 ml. of tri-o-cresyl phosphate and 4 ml. of tetrahydrofuran was emulsified by means of a small homoblender in 20 ml. of ana queous solution kept at 60 C. and containing 0.1 g. of an anionic surface active agent (A-ll) and 2.0 g. of gelatin. The whole of the dispersion thus obtained was added to g. of a red-sensitive emulsion containing 7.0 g. of gelatin and 3.3x l0=- mole of silver chlorobromide. The photographic emulsion was applied at a dry thickness of 5 microns to a triacetylcellulose film base coated with an anti-halation layer. A photograph of a figure drawn on a white paper with a black ink was taken on the film thus obtained and the film was then processed in the same manner as in Example 2 to obtain a slide for display having distinct yellow lines and letters on a blue background.

What is claimed is:

1. A process for producing a color photographic sensitive material comprising a support and a silver halide emulsion layer containing a finely dispersed libophilic color forming coupler free of water solubilizing groups, in which said coupler having at least a hydrophobic radical containing 9 to 28 carbon atoms, while liquefied, is dispersed in an aqueous gelatin solution in the presence of (1) a nonionic surface active agent obtained by esterification of one to two hydroxyl groups in an anhydrohexitol molecule with a fatty acid containing 10 to 20 carbon atoms; (2) an anionic surface active agent having both a hydrophobic radical containing 8 to 30 carbon atoms and a water-solubilizing MO S- or MO SO-group wherein M represents a hydrogen atom, an alkali metal atom or an ammonium group; and (3) an organic solvent which is substantially insoluble in water, said color former being added to said aqueous gelatin solution while liquefied in said organic solvent.

2. A process as claimed in claim 1 in which said coupler has a phenolic group.

3. A process as claimed in claim 1 in which said coupler has a pyrazolone nucleus.

4. A process as claimed in claim 1 in which said coupler has an acylacetanilide radical.

5. A process as claimed in claim 1 in which said anionic surface-active agent is selected from the group consisting of an alkylarylsulfonate, an alkylsulfonate, an N-acyltaurine, an N-acyl-N-al-kyltaurine, an alkylfulfonate or a dialkyl-a-sulfosuccinate.

6. A process as claimed in claim 1 in which said anionic surface-active agent has a coupling radical selected from the group consisting of a phenolic and naphtholic radical, an acylacetanilide radical and a 5-pyrazolone radical.

7. A process as claimed in claim 1 in which said anhydrohexitol is sorbitan or anhydromannitol.

8. A process as claimed in claim 1 in which the amount of each surface-active agent ranges from 0.05 to 0.5 weight part per 1 part of coupler.

A process as claimed in claim 1 in which said non- 1onrc surface-active agent is selected from the group consisting of sorbitan sesquioleate, sorbitan, monooleate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monolaurate mannitane monooleate or mannitol monooleate Y csu ocrncazocmog soma 10. The process of claim 1 wherein said color-forming coupler is emulsified in said aqueous gelatin solution.

11. The process of claim 1 wherein said gelatin has an 5 average molecular weight greater than 30,000. GHQ-000C831? 12. The process of claim 1 wherein said color-forming coupler is dispersed into said gelatin solution in the form l2 25 S OaNa. I

of a melt further wherein said coupler has a melting point below about 90 C. r. H 13. The process of claim 1 wherein said color-forming coupler is initially dissolved in a solvent and then dis- CHHWCONH TSOiN" persed in said gelatin solution. a

14. The process of claim 1 wherein said coupler contains a coupling radical selected from the group consisting of a phenolic radical, a naphtholic radical, an acylaceto- Y O anilide radical and a S-pyrazolone radical. v Na as 15. The process of claim 1 wherein said nonionic sur- 1.

face active agent has an HLB of from 3,5 to 9.5. N

16. The process of claim 10 wherein said color-forming coupler is emulsified in said aqueous gelatin solution to a size of from 0.1 to 0.4 micron. 1 Y

17. The process of claim 1 wherein said organic solvent p is substantially insoluble in water and has a boiling point r v V at normal pressure above 190 C. C1BH310 1C OQHQCONHTQ 18. The process of claim 17 wherein said solvent is selected from the group consisting of esters of carboxylic I s O acids, phosphate esters, carboxyl amides, ethers and bydrocarbons.

19. The process of claim 17 wherein said organic sol- 3 vent is selected from the group consisting of di-n-butyl fiphthalate, di-isoctyl phthalate, di-methoxyethyl phthalate, N di-n-butyl adipate, di-isooctyl azerate, tri-n-butyl citrate, butyl lauratc, di-n-butyl sebacate, tricresyl phosphate, -trin-butyl phosphate, tri-isooctyl phosphate, N,N-diethylcaprilamide, N,N-dimethylpalmitamide, n-butyl-m-penta- Y decylphenyl ether, ethyl 2,4-tertbutylphenyl ether and I I SO3H chlorinated paratfins.

20. The process of claim 1 wherein there is present in 0 addition to said organic solvent a member selected from 40 the group consisting of a low boiling solvent and a watersoluble high-boiling solvent.

21. The process of claim 20 wherein said member from said group is selected from the group consisting of propylene carbonate, ethyl acetate, butyl acetate, ethyl propionate, sec. butyl alcohol, tetrahydrofuran, cyclohexanone, dimethylformamide, diethylsulfoxide and methyl Cellosolve. r N

22. The process of claim 1 wherein said gelatin is selected from the group consisting of acid-treated gelatin, l limed gelatin and enzyme-treated gelatin. I t

23. The process of claim 1 wherein said coupler contains a coupling radical which couples with the oxidation product of an N,Np-phenylene diamine.

24. The process of claim 1 wherein said anionic surface active agent is selected from the group consisting of r O CuHzuO S aNa Turkey red 01] CuHzsC ONHCHzCHgO S OaNB.

and 

